Automatic control of railway classifi-cation yard track switches



Dec. 9, 1958 B. MISHELEVICH 2,863,991

AUTOMATIC CONTROL OF RAILWAY CLASSIFICATION YARD TRACK SWITCHES FiledMay 15, 1953 8 Sheets-Sheet 1 Fig 2i fig Z9 4 Hp? 20. Fig .?b. Fig 20.Fig 20!. Fig 2e.

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HIS ATTORNEY Dec. 9, 1958 B. MISHELEVICH AUTOMATIC CONTROL OF RAILWAYCLASSIFICATION YARD TRACK SWITCHES Filed May 15, 1953 8 Sheets-Sheet 3Fi 2b.

Dec. 9, 1958 B. MISHELEVL H 2,863,991

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AUTOMATIC CCNTROL 0F RAILWAY CLASSIFICATION YARD TRACK SWITCHES FiledMay 15, 1953 I 8 Sheets-Sheet 8 1-ZA$0R FZASFPSI? 1? I an 1 15 w Fig 29:

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HIS ATTORNEY United States Patent AUTOMATIC CONTROL OF RAILWAY CLASSIFI-CATION YARD TRACK SWITCHES Benjamin Mishelevich, Pittsburgh, Pa.,assignor to Westinghouse Air Brake Company, Wilmerding, Pa., acorporation of Pennsylvania Application May 15, 1953, Serial No. 355,281

6 Claims. (Cl. 246-2) My invention relates to automatic control ofrailway classification yard track switches, and particularly to animproved system for automatic control of railway classification yardtrack switches, in which, with a minimum amount of apparatus, improvedoperation is obtained in that the routing of cars through the yard isspeeded up because less spacing is required between successive cars orcuts of cars. Furthermore, information as to the routing of successivecars or cuts of cars is presented to the operator of the system in suchmanner as to facilitate more rapid operation of the system.

A hump yard classification system is a yard of railway tracks and trackswitches, wherein a single track preferably leading from a hump or hilldiverges into a large number of storage tracks through suitable trackswitches. In practice, cars, or cuts of cars as they are sometimescalled, are allowed to run down the hump in close succession, each caror cut of cars going to a particular storage track. In practice, a largenumber of such cars, or cuts of cars, follow each other off the hump inclose succession, and in order that a track switch may assume the properposition when a particular car reaches it, it is often necessary thatthe track switch be operated immediately upon the vacancy of thedetector track circuit associated therewith by the car next in advance.In other Words, the requirement of time of operation of track switchesis often so precise that automatic control of the track switches isdesirable in order that a track switch may be operated as soon as itsdetector track circuit becomes unoccupied by a preceding car. Since thecars to be classified may be so closely spaced that several differentlyclassifiable cars may occupy the same stretch of non-track-circuitedtrack between two successive track switches, it is necessary to havesuitable train describer storage apparatus which will store, so tospeak, the destination each particular car or several cars is to take,so that this stored indication may operate the track switch before thecar designated thereby reaches such track switch. In modern hump yardtrain classification systems the cars or cuts of cars are retarded bysuitable track brakes or retarders, which track brakes are controlledfrom a control tower located below the hump and from which tower thedistribution and storage tracks are clearly visible. Additionally, insystems wherein the track switches aremanually controlled, the usualpractice is to have the manual control levers for the operation of thetrack switches on the same control board as the control apparatus forthe car retarders, so that the towerman controls both the routing of thecars and the retardation as the cars pass along the various leads totheir final storage tracks. In the use of a system for automaticallygoverning the track switches, the car or cut description stored in thesystem is preferably registered therein by the control tower operator,so that thereafter he need only be concerned with controlling theretardation of the various cuts of cars as they pass down the hump,since the switches will automatically be operated in advance of each cutof cars to route the cars to their proper storage track.

It has previously been proposed to provide systems of the typedescribed, which comprise an arrangement of manually operable contacts,relays and circuits, which relays are neutral relays many of which areprovided with various stick or holding circuits. These systems arearranged to employ a plurality of relay storage banks, the number ofstorage banks in each storage unit being set so that all of the carsthat may occupy a stretch of track leading to a particular track switchwill have their descriptions stored therein, one description for eachstorage bank. Each of these storage banks includes three kinds orcharacters of relays. Each storage 'unit includes storage detectorrelays which when energized indicate that a train description or routingis stored in .the associated bank of such a unit, switch storage relayswhich designate the route that the approaching cut of cars is to take,and storage transfer relays which determine when a route description maybe transferred from one storage bank to the next successive storagebank.

The route descriptions are usually entered into the apparatus by theoperation of push button or other manually operable contacts whichdesignate the final storage track to which the particular car or cut ofcars is assigned. Theoperation of these contacts stores in the initialunit of the apparatus the route description for the cut of cars, in adigital form, that is, by providing a storage relay for each storagetrack in the classification yard. In systerns previous to the onedisclosed in this application, it has been the practice to translate thedigital route storage in the initial bank to a combination code, that isto energizea plurality of busses or code wires in a particularcombination which determines the route of the cut of cars. Additionalbanks of combination storage relays are then provided, so that aplurality of route descriptions may be stored in the initial unit of thesystem.

However, with this type of arrangement, the provision of indications tothe operator of the system as to the routes which are stored in thesystem is difficult from the standpoint that complicated translationcircuits are required if the information is to be presented to theoperator in sequential form, that is, if the operator is to be givenindications of the storages which exist in the initial storage unit ofthe system, in the sequence in which they are entered in'the system.Accordingly, one object of my invention is to provide a system of thetype described in which the initial storages in the system are containedin a system of digital storage relays, of which a plurality of banks maybe provided, with the storage in each bank being transferred to the nextsucceeding bank when the succeeding bank is in the position to receivean incoming storage. The storage relays in each bank of the initial unitare provided with circuits which govern indicators to advise theoperator of the equipment of the condition of the initial storage unitboth as. to the capacity remaining in the unit and the specificdescription of the cars or cuts of cars which have been entered in theunit.

The route descriptions stored in the final bank of digital storagerelays in the initial unit are translated into a combination code, whichis transferred to succeeding storage units, though the operation ofstorage detector and storage transfer relays, as well as by relays whichare governed by the occupancy of a detector section of the track switchby a car or cut of cars. In the succeeding storage units following theinitial stor age unit, the route descriptions are stored as acombination code, this arrangement requiring fewer relays than if thedigital code were maintained throughout the system. As in the previoussystems, the apparatus is arranged so that the energized or deenergizedcondition of a switch storage relay in one of the storage units otherthan the initial unit determines whether or not the switch associatedwith that unit will be positioned to its normal or reverse position Ifthe switch is to remain in its normal position, the switch storage relaywill remain decnergized, but if the switch is to be reversed, the switchstorage relay will be energized and its contacts picked up. The circuitsare constructed and arranged in such manner that the switch storagerelays may all remain released for a particular route, in which allswitches are to be positioned in their normal positions, in which casethe route description is obtained through the use of the storagedetector and transfer relays of the various units following the initialunit.

In systems of this type as previously proposed, it is necessary toprovide a storage unit for each of the switch locations in aclassification yard automatic switching apparatus. Accordingly, wherelap switches are employed to conserve space in a classification yard,such lap switches being arranged so that the switch point of one of theswitches falls between the switch points and the frog of a precedingswitch, it may be necessary to provide an additional storage unit, togovern the operation of the first and second switch of the lap switchlayout. However, an object of my invention is to provide an arrangementfor a system of the type described in which the operation of the twoswitches of the lap switch layout is governed by a single set of switchstorage relays, together with their storage detector and transferrelays, by the provision of one auxiliary relay which is governed insuch manner as to insure the proper positioning of the two switches ofthe lap switch combination.

A further object of my invention is to provide an automatic switchingsystem for railway track switches in a railway classification yard,which system may be readily expanded to govern these switches in alayout of any size.

Other objects of my invention and features of novelty thereof willbecome apparent from the following specification, taken in connectionwith the accompanying draw ings.

In practicing my invention I provide a system of interconnected relaycircuits arranged in groups designated as storage units. In general, onestorage unit is provided for each switch location in the classificationyard. Within each of the storage units, the relays and circuits arefurther sub-divided into storage banks. One storage bank is provided foreach route description to be stored in such storage unit at anyparticular time, as determined by the construction of the classificationyard and the number of cars or cuts of cars which can be moving throughthe yard between successive switches at any one time. The routedescriptions are entered in the sys tem by operation of suitableswitches, such as manually operated push buttons, in accordance with thestorage tracks to which the cars or cuts of cars are to be routed, andin the order in which the cars or cuts of cars enter the classificationyard. These contacts control a plurality of digital storage relays inthe first, or initial bani; of the initial storage unit. The routedescriptions are represented in the initial bank by the picked up orreleased condition of the digital storage relays, the relay associatedwith a particular route being picked up when the route is entered in thestorage unit. Additional banks of digital storage relays in the initialstorage unit are provided, in order that a predetermined number ofroutes can be stored therein, by cascading the route description fromthe first storage bank to the subsequent storage banks, provided thesebanks are empty, i. e., none of the storage relays in that bank arepicked up. The route descriptions stored in the storage banks of theinitial storage unit are indicated to the operator by a plurality oflamps governed by the digital storage relays, one lamp being associatedwith each relay. Transfer of the route storages from one bank to thenext is accomplished through the medium of a storage transfer relay anda storage detector relay associated with each storage bank, the storagetransfer relay acting to energize the storage relays of the succeedingbank in accordance with the energization of the storage relays in thepreceding storage bank, providing the storage detector relay indicatesby its released condition that the succeeding bank is vacant. i e., thatnone of the storage relays in that bank are picked up.

The storage relays in storage units subsequent to the initial storageunit are arranged to store the route description in a combination codeform, which is a simpler and more economical manner of storing the routedescriptions where numerical indications are not required. This type ofstorage is obtained in my invention by providing as many storage relaysin each storage bank as the maximum number of switches which can betraversed by a car or cut of cars after passing the location with whichthe particular storage banks are associated. Each of these switchstorage relays in a particular bank dcfines the position which aparticular switch is to take for the route description stored in thatbank, the switch being controlled to its normal position if the switchstorage rclay is deenergized and being controlled to its reverseposition if the switch storage relay is energized.

In the system proposed by my invention, the route descriptions areforwarded from one storage unit to the next upon the occupancy of thedetector track section associated with the storage unit. This operationis governed by a storage transfer repeater stick relay and a storagedetector repeater stick relay governed by the detector track relay ofthe associated track switch, in such manner that the repeater stickrelays can function only once during a track circuit occupancy toforward a route description from the final bank of the associatedstorage unit to the initial bank of the succeeding storage unit.

The control of the track switches is accomplished by circuits includingcontacts of the associated switch storage relay. The usual detectorlocking is provided by carrying the main switch control circuits overfront contacts of the detector track relay. In order to provide forpositive operation of the switch to one or the other of its twopositions in the event that the main switch control circuits are openedduring the operation of the switch, I provide auxiliary switch controlcircuits governed by contacts associated with the switch and by a backcontact of the associated track relay so that if the switch detectortrack section is occupied during the transit of the switch, the switchwill be operated to the final position to which it is closest at thetime.

In order to control the operation of the second switch in a lap switchlayout, where separate detector sections are provided, my inventionincludes the provision of an auxiliary relay which includes in itscontrol circuit the switch storage relays (or the digital storagerelays, in the event that the lap switch is the first switch in the yardlayout) of the second preceding bank in the associated storage unit.Contacts of this auxiliary relay are interposed in the switch controlcircuit for the first lap switch of the lap switch layout so that thefirst lap switch may be operated to the proper position for a followingcut of cars as soon as a preceding cut of cars has vacated the first ofthe overlapped detector track sections.

I shall describe one form of automatic control of railway classificationyard track switches embodying my in vcntion and shall then joint out thenovel features there of in claims.

In the drawings, Fig. is a diagrammatic view of a classification yardequipped with an automatic switching control system according to myinvention.

Figs. 2a, 2b, 2c, 2d, 20, 2) and 2g illustrate, diagrammatically, theautomatic switching control circuits for Fig. 1.

Fig. 3 is an assembly diagram for Figs. 2a, 2b, 2c, 2d, 22, 2] and 23.

Similar reference characters refer to similar parts in each of theseveral views.

Referring to Fig. 1 of the drawings, there is shown, in schematic form,the layout of track switches in a six track classification yard, whichis equipped with an automatic switching system constructed in accordancewith my invention. As shown, the single lead track at the left divergesthrough various switches to six storage tracks, numbered consecutively1, 2, 3, 4, 5 and 6 from bottom to top at the right-hand end of thetrack layout. At the left or hump end of the layout, there is shown acontrol tower at which point the control equipment may be disposed, andfrom which point the operator governs the operation of theclassification yard. Each of the track switches is provided with asuitable power operated switch movement designated by the referencecharacter SM, preceded by a hyphenated number combination whichindicates the tracks to which the switch leads. For example, 1-2SM isthe switch movement associated with the switch which diverges the car orcut of cars to track 1 or track 2. Each of the single switch locations1-2, 34 and 5-6, is provided with a suitable type of track circuit, hereshown as a conventional direct current track circuit including a trackbattery connected across the rails at one end of the section and a trackrelay connected across the rails at the other end of the section. Thesetrack relays provide detector locking for the switch with which they areassociated, so that the switch cannot be operated under the wheels of acar or cut of cars which is traversing the switch. It is to beunderstood that various types of track circuit arrangements may beemployed, and my invention is not limited to use with direct currentneutral track circuits of the type shown. As previously pointed out,each of the track circuits for the single switches is provided with atrack relay, which is designated by the reference character TR, precededby the number of the switch, as for example, 12TR.

The first two switches in the layout, namely, 1-6 and 1-4 comprise whatis known in the art as a lap switch. Such an arrangement is employedwhere it is desired to conserve space, and is constructed and arrangedso that the switch points of the second switch in the layout, in thiscase the switch l4, fall between the switch points and the frog of thefirst switch, in this case 1-6. In connection with the lap switch layoutas shown in Fig. 1, there is provided a special track circuitarrangement for providing the proper detector operation for the controlof the two lap switches. This arrangement includes a track battery 16TBand 3 track relays, 16TR, 16ATR and 14TR. This track circuit arrangementis fully shown and described in Letters Patent of the United States No.1,797,561, issued to Howard A. Thompson on March 24, 1931. The operationof the track circuit arrangement as shown in Fig. 1 is explained indetail in the aforementioned Thompson patent. It is deemed sufficient topoint out herein that the apparatus is arranged in such mannerthat trackrelay 1-6TR will be released at any time that a car or cut of cars isoccupying the stretch indicated by the reference character P togetherwith the limits shown by the arrows associated with this referencecharacter, and that relay 1-4TR will be released at any time that thestretch of track between the limits indicated by the reference character0 together with the arrows associated therewith is occupied by a car orcut of cars. Accordingly, as a car or cut of cars approaches theswitches 16 and l4 from the hump, the switch movement 1-6SM will belocked by the release of the track relay 16TR as soon as the first pairof wheels of the car or cut of cars passes the first pair of insulatedjoints at the left-hand end of the track Stretch. Switch 1--6 willremain locked until the last pair of wheels has passed off the insulatedjoint located'at the right-hand end of the limits indicated by thereference character P. Also, the switch movement 1-4 will become lockedas soon as the first pair of wheels passes the insulated joint at theleft-hand limit shown to the left of the reference character 0, and willremain locked until the last pair of wheels passes the limit indicatedto the right of the reference character 0.

Throughout the drawings, it will be found that the contacts associatedwith each of the relays shown in the circuit arrangement are arranged ina vertical line with the operating winding of the relay, with theexception of the contacts of the track relays, in which case, anoperating winding is shown associated with the track relay contacts, andit will be understood that this winding is connected as shown by Fig. l.T

The circuits for providing the automatic control of the switches shownin Fig. 1 are shown in Figs. 2a through 2g when these drawings arearranged in the manner shown in Fig. 3.

In the control tower, there is provided a control board or machine whichincludes a plurality of manually operated contacts such as the pushbuttons designated by the reference characters lPB through 6PB, Fig. 2a.One push button is provided for each of the storage tracks in the yard,in this instance, the tracks 1 through 6. Associated with each of thepush buttons is a series of digital storage relays, such as the relays1-6C1CR, 1-6B1CR and 1-6A1CR, Fig. 2a, associated with the push buttonllPB. Additionally, located at a convenient point on the control machinefor observation by the operator are a plurality of indication lamps,such as the lamps All through A6, B1 through B6, and C1 through C6, Fig.2a, which are employed to indicate to the operator of the machine whatroute storages are present in the initial storage unit of the apparatus.The digital storage relays, such as relays 1-6C1CR, 1-6B1CR, and 16A1CRare arranged and governed in such manner that these relays govern thestorage routes which are put into the machine by operation of the pushbuttons in the sequence in which the cars or cut of cars coming oil? thehump are to be routed to their various storage tracks. The controlcircuits for the initial digital storage relays are arranged in suchmanner that the operation of the push button causes the associated relayin the initial or C bank to be picked up, provided no other relay inthat bank is picked up. With a particular initial digital storage relaypicked up in the C bank, the corresponding relays in the B and A bankswill pick up in sequence, provided that these banks are empty.Accordingly, a route description entered into the initial storage unitis cascaded from the initial digital storage relay to the final digitalstorage relay as long as the following bank is empty. Since the routestorage indication lamps are governed by contacts on the digital routestorage relays, these lamps will operate in sequence to indicate theposition of the route storage. That is, for example, if the operatordepresses push button lPB, relay 1-6C1CR will pick up to thereby lightindication lamp C1. Upon picking up the relay 1-6C1CR, circuits areestablished which detect whether or not the subsequent storage bankscontain a route information, that is, whether or not one of the routestorage relays in the next bank is picked up, and if the banks are emptythe route storage is cascaded through to the final bank- In theparticular instance cited, the relays 1-6B1CR and 16A1CR would becomepicked up in sequence, so that lamps B1 and A1 would light in the samesequence. It is of course necessary that the transfer of the storagefrom one bank to another releases the storage relay in the precedingbank, so that in effect, the operation of push button lPB will cause thelamps C1, B1 and A1 to be lighted in the sequence named, with the lampA1 remaining lit as long as the storage remains in the initial storageunit. It will be apparent that the initial storage unit is not limitedin its capacity either to the number of tracks or routes which are to bestored therein, or tie number of storages made possible, since thecircuits may be readily expanded to take care of any number of routedescriptions and any number of storages for these route descriptions.From the foregoing. it will be seen that the route descriptions arestored in the initial storage unit in the manner of a digital code, thatis, a relay is provided for each of the possible routes, in each of thestorage banks in the initial storage unit. In this manner, it iscomparatively simple to provide a route storage indication lamparrangement of the type shown. in which individual lamps representingthe various routes are lighted for each storage in the initial unit.

The transfer of the route storages from one bank to another in thevarious storage units is made through the medium of the operation ofstorage transfer relays l storage detector relays, together withrepeating stick rc lays of each storage transfer relay and storagedetector relay for the final bank of each unit. For example, in theinitial unit there are provided storage transfer relays 16CSTR, l-6BSTR.and l.-6ASTR. Fig. 2b, corresponding to the three banks C, B and A,respectively. in the initial storage unit. Likewise there are providedthe storage detector relays 1-6CSDR, l6BSDR and l fiASDR, Fig. 21 in thefinal or A bank of the initial storage unit there are also provided therepeater stick relays 1(ASDPSR and l-6ASTPSR, Fig. 2c. These relaysserve to provide means for transferring the route descriptions stored inthe various banks of the storage unit from one bank to the next bank inaccordance with whether or not the following bank is occupied by a routedescription. Additionally, the storage detector relays and the storagetransfer repeater stick relays in the final or A banks of each of theunits are governed in part by the contacts of the track relay associatedwith the switches. to thereby provide for advancing the routedescription from one storage unit to another as the car or cut of carsassociated with the route description moves through the various detectorsections as it passes from the hump to the storage track. The operationof these relays will be explained in detail subsequently.

As previously explained, the route descriptions are stored in theinitial storage unit in the form of a digital code, in order to renderthe provision of route Storage indications possible by relatively simplecircuits. lowever, following the initial storage unit, the routedescriptions are stored in subsequent storage units in the form of acombination code, that is, a group of switch storage relays are providedwhich are arranged to be piclccd up or released in differentcombinations depending upon the route stored in the particular unit. Thetranslation from the digital code to the combination code is provided inthe initial storage unit. and the route descriptions are cascaded fromthe initial storage unit to the subsequent storage unit for thefollowing track switches in the layout by combination code busses. Thecombination code storage is provided by switch storage relays which whendeenergized indicate that the associated switch is to take one position,and when energized indicate that the associated switch is to take theother position. For the pnr poses of this disclosure. it will beconsidered that a switch is occupying its normal position when it is setto divert traffic to the left as a car or cut of cars approaches theswitch from the hump. and it will be considered to be in its reverseposition when it is set to divert a car or cut of cars to the right asthe car or cut of cars proceeds over the switch from the hump. Theswitch storage relays in the initial unit are governed by circuitsincluding contacts of the digital route storage relays, in such mannerthat the pick up of one or more of the digital storage relays in thefinal bank will energize a particular switch storage relay, and theenergization of this switch storage relay will cause the operation ofthe associated switch to its reverse position, whereas if the particularroute description stored in the digital storage relays does not all.)

it energize a particular switch storage relay, the switch associatedwith that relay will remain in its normal position.

Power for the operation of the relays other than the track relays isobtained from a suitable source, such as the batter LB shown, the powerbus BA including it normally closed contact of a push button CSPB. Thepower for the various indication lamps is obtained from a suitablealternating current source such as the transformer iT. the power bus BXalso including a closed contact PEPE. These power supplies are shown Inorder to provide for the cancellation of improperly 'stercd routedescriptions in the apparatus, several can- "ttinn push buttons areprovided which when operated l the dc: rip-tien contained in certainparts of the system. The cancellation button for clearing the system,CSPB. is arranged so that when this push button is operated the supplyof energy to certain of the circuits in the initial storage unit is cutoff. so that all of the digital route storage relays in the initialstorage unit are released. An additional contact on the clear systempush button CSPB is provided in the circuit for supplying energy tolight the various indication lamps, so that during the time that thesystem is being cleared, the lamps will remain dark and not llash orblink. Operation of this push button cancels all the route storages inthe initial bank. in the final bani; of each of the storage units thereis provided a cancellation push button such as the push button l6ACPB,Fig. 2/), which when operated cancels the route description stored inthe final bank of the associated unit. Additionally, there is providedfor the initial unit a cancellation push button l'6CC. Fig. 2/), whichwhen operated cancels the route descriptions in succession from theinitial bank to the final bank of the storage unit. By operation of thispush button, the routes stored in the banlzs oi the initial storage unitmay be cancelled by operating the push button the same number of timesas the number of the storage which it is desired to cancel. This pushbutton governs the operation of storage cancellation relays such asrelays I6CSCR. 1--6BSCR and 1(.ASCR. Fig. 2/), which are governed insuch manner that these relays are picked up in sequence as the pushbutton is operated, to thereby cancel the route descrip tion in thestorage bank associated with the cancellation relay.

Each of the trucl; switches, such as, for example, switch l(, isprovided with a switch movement such as 1-6SM, Fig. 2 which may be ofany suitable type, and is herein shown and described as being of thedirectacting clectropneumatic type switch machine, one such type beingshown and described in detail in Letters Patent oi the United States No.2,092,828, granted to Herbert L. Bone on September 14, 1937. Associatedwith each of the switch movements or machines, there is; provided anormal and a reverse switch repeater relay. such as relays 16NWPR and1-6RWPR, Fig. 2 which serve to govern the various route selectioncircuits for cascading the route descriptions through the proper storageunits in accordance with the routes as set up in the initial storageunit. The apparatus also includes a switch restoring relay such as relay1-6WPR, Fig. 2f, which is arranged to operate in such manner that therelay tune tions to restore the switch to its normal or reverse positionin case the switch does not complete its operation within a specifiedtime, such as might be due to an obstruction at one of the switchpoints. In order to provide manual control of the switches at times whenit may be desirable, such as during trimming operations, to manuallygovern the position of the switches, a threeposition switch controllever such as lever 1-6NIC, Fig. 2c, is provided for each of the trackswitches. When this lever is positioned in its usual or center position,circuits are completed for governing the operation of the associatedswitch movement automatically in accordance with the route descriptionsin the system. When the switch lever is moved to one or the other of thetwo extreme positions, the switch movement is operated to its normal orreverse position in accordance with the posi tion of the lever,provided, of course, that a car or cut of cars is not occupying thedetector track circuit including the switch. Normal and reverse switchindication lamps, such as, for example, 16NWK and 16RWK, Fig. 2 areprovided on the control machine to indicate to the operator of themachine the actual position of the switch points. The circuits forcontrolling the switch indication lamps are arranged in such manner thatthe lamps are lighted as the route description is provided for theoperation of each switch in the route in advance of the car or cut ofcars, so that the switch indication lamps also serve as routeprogression lamps on the control board. Each of the track relays governan indication lamp on the control board, which lamps when lightedindicate that the detector section associated with the track relay isoccupied, such as lamp 16TK, Fig. 20, which is governed by track relay16TR. Each of the switch movements is provided with a plurality ofcontacts, such as the contacts X, Y and Z shown in connection with eachof the switch movements on the drawings,-with these contacts arranged toopen and close in such a sequence that carry through carry backoperation is secured. In this type of operation, the parts areconstructed and arranged in such manner that if the switch movementbegins to operate from one position to the other, the movement willcontinue operation even though a car enters the detector section,provided the switch has passed its center position. If the switch hasnot reached its center position at the time the track relay is released,indicating the entrance of a car or cut of cars into the detectorsection, the switch is restored to the position from which it started.

Description of operation It is believed that a description of theoperation of the switching system will provide a clear understanding ofthe invention by describing it under various conditions of operation.

It will first be assumed that there are no route descriptions stored inany of the storage units and that all of the manual switch controllevers are in the automatic position, and additionally, that there areno cars moving over the leads from the hump to the various storagetracks. Assuming that the first car proceeding from the hump is to berouted to storage track 1, the operator in the control tower willdepress push button 1PB, Fig. 2a.

When the push button llPB is depressed momentarily by the operator, apick up circuit for relay 16C1CR is established, which circuit may betraced from terminal B at back contact h of relay 16BSTR, Fig. 2b, overback contact a of relay 16CSDR, over contact a of lPB and through thewinding of relay 1--6C1CR to terminal N. The back contact h of relay1-6BSTR provides a check that no transfer is in progress from the C tothe B bank of digital storage relays in the initial unit, and the backcontact a of relay 16CSDR checks that the bank C does not have a digitalstorage relay picked up, in other words, that the bank C is empty atthis time. It will be seen that the pick up circuit for the variousdigital storage relays in the initial or C bank of the initial storageunit are checked over the back contacts of the preceding push buttons,so that'a check is provided that only one push button may be operated ata time, and in case two push buttons are depressed simultaneously withno storages in the C bank, the lower- 'numbered digital storage relaywill be picked up, and no other relay may be picked up at this time.

When relay 16C1CR picks up, it establishes a stick or holding circuitfor itself which circuit may be traced from terminal BA at back contacta of relay 16CSCR,

, and as previously pointed out, the back contact a of relay 1- 6CSDR isprovided .in the pick up circuit over the contact of the push button, sothat at this time with relay 1--6C1CR picked up no further routestorages, can be entered in the initial or C bank of the initial storageunit. At this time, a circuit is established for supplying energy to theroute storage indication lamp C1, which circuit may'; be traced fromterminal BX over back contact e of -relay,1 --6C SCR, Fig. 2b, fromcontact b of relay 16CSTR, front contactc of relay 16CSDR, over frontcontact a of relay 1- -6C1CR, and through the lamp C1 to terminal N-X.Accordingly, the indication lamp bank will show thata route descriptionto storage track 1 is stored in bank C of-,the"initialstorage unit.

' WhenreIay 'I- -GCSDR picks up, its front contact d .establishes acircuit 'for supplying energy to the winding of relay 16BSTR; whichcircuit may .be traced fromterminal B at front contact d .of relay16CSDR, .Fig. 2b, over back Contact of relay 1'6BSDR, and :through thewinding of relay 16BSTR to terminal N. The back contact 1 of relay1-6BSDR checks that the .B bank in the initial storage unit contains 'noroute description. When relay 16BSTR picks up, two stick circuits areestablished for. maintaining the relay energized. -The first of thesestick circuits includes a contact b of each of the pushbuttons lPB to6PB, which .insures that only. one storage may be entered into thesystem and transferred from the C bank'to the B bank with one operationof, the push button. This circuit includes front'contact a of relay16BSTR, and the conta'cts bmf. each of; thepus'hbuttons. The secondstick circuit forrelay 16BSTR includes front contact b of relay 16BSTRand front contact d of relay 1 6CSDR, this circuit being provided toinsure that relay 1 6BSTR will remain picked up while the routedescription is being transferred from the digital route storage relaysin bank, C, of the initial unit to bank B -of the same unit.

'When relay 16BSTR picks up, a circuit is established for supplyingenergy to the winding of relay 16BSDR, which circuit may be traced fromterminal BA at back contact b of relay 16ASTR, Fig. 2b, and

terminal BA at back contact 1 of relay 16ASDR, Fig. .2b, over frontcontact .1 of relay 16BSTR, .through the winding of relay 16BSDR, andover back contact d-of relay 16BSCR to terminallN. When relay 1 6BSDRpicks up, its from contact 0 will establish a stick, circuit for therelay which bypasses the front contact f of relay 1-6BSTR, so that relay16BSDR will remain picked up subsequent to therelease of relay 16BSTR. pY

With relays 16BSTR, 16BSDR and relay 1-,6C1CR picked up, a. circuit isestablished .for transferring the route description stored in-bank' C byrelay 16C1CR, to bank B, by picking up relay 16B1CR. The pick up circuitfor relay 16B1CR may be traced fromvterminal B at front contact g ofrelay 16BSTR,

Fig. 2b, through the blocking rectifier K, over front contact c of relayl-ASCICR, through the winding of relay 16B1CR, and over front contact gof relay 16BSDR to terminal N. When relay 16B1CR picks up, itestablishes a stick circuitfor itself including front contact a of relay16B1CR, the winding of the relay, and the front contact g of relay16BSDR. It will be noted that the pick up circuit for each of thedigital storage relays in banks A and B of the initial .storage unit areprovided withblocking rectifiers. These rectifiers are poled in suchmanner that pick up energy may flow therethrough to .pick up theassociated digital storage relay, but energy cannot flow through therectiwinding of relay 1 fier when the stick circuit of the associatedstorage relay is closed. This arrangement prevents run-around circuits,or sneak circuits, from occurring in the pick up circuits of the variousdigital storage relays in the banks of the initial storage unit.

Relay I6CSTR is governed by a circuit including back contact of relay16BSTR and back contact a of relay 16BSDR. With relays 1-6BSTR and16BSDR both picked up, the energizing circuit for relay 1 GCSTR will beopen. However, relay 1-6CSTR is selected and arranged so that it is slowin releasing its contacts, and accordingly the contact of the relay willremain picked up for an interval of time which is sufiicient for thedigital storage relays in the second or B bank of the unit to pick upand close their stick circuits. At the expiration of the release time ofrelay 16CSTR, front contact a of relay 1-6CSTR opens and therebyinterrupts the supply of energy to the stick circuit for relay 16C1CR,so that relay 16C1CR releases. The release of contact 0 of relay 1-6C1CRinterrupts the previously traced pick up circuit for relay 1-6B1CR, butrelay 1-6B1CR remains picked up at this time because of its previouslyestablished stick circuit including front contact a of the relay.Additionally, when contact :1 of relay 1-6C1CR releases it interruptsthe circuit for supplying energy to the route storage indication lampC1, so that this lamp is extinguished thereby denoting that no routestorages are in the C bank of the initial storage unit. The release ofcontact I) of relay 1--6C1CR opens the previously traced circuit forsupplying energy to the winding of relay 1-6CSDR, and accordingly therelay 16CSDR releases. If at this time the operator has released thepressure upon the push button lPB, the previously traced stick circuitfor relay 1--6BSTR including front contact a of relay 1--6BSTR is openand the release of relay 1-6CSDR opens the other stick circuit for relay1-6BSTR which includes front contact b of relay 1--6BSTR and frontcontact d of relay 1-6CSDR. At this time, therefore, the routedescription is stored in the B bank of the initial storage unit, byvirtue of the picked up state of digital storage relay 1-6B1CR. At thistime, a circuit is established for supplying energy to the lamp B1 ofthe route storage indication lamps which circuit may be traced fromterminal BX at back contact a of relay 16BSTR, Fig. 2b, over frontcontact h of relay 1--6BSDR, front contact c of relay 16B1CR, andthrough the lamp B1 to terminal NX. Accordingly, the operator will beprovided with an indication that a route storage to storage track it ispresent in the second or B bank of the initial storage unit.

When relay 1--6BSTR releases, its back contact c again establishes thecircuit for supplying energy to the relay 16CSTR, and relay 16CSTR picksup so that contact a of relay 1-6CSTR which governs the stick circuitsfor the first or C bank of digital storage relays in the initial storageunit is again closed, so that a subsequent storage can be now entered inthe initial or C storage bank of the initial storage unit.

The route storage stored at this time in the B bank of the unit is nowtransferred to the final or A bank of the unit by the following sequenceof relay operation. When relay 1-6BSTR releases, its back contact eestablishes a circuit for supplying energy to the winding of thetransfer relay 1-6ASTR, which circuit may be traced from terminal B atback contact 0 of relay l-'6BSTR. Fig. 21 over contact 12 of relay1-6BSDR, back contact of relay 1-6ASDR, and through the GASTR toterminal i. When relay l6ASTR picks up, its front contact a closes astick circuit for the relay which circuit bypasses back contact b ofrelay l-6ASDR. The picking up of relay 16ASTR establishes a pick upcircuit for the storage detector relay l-6A'SDR, which circuit may betraced from terminal BA at the cancellation push t button 1-6ACPB,Fig.2!), over back contacta of relay 16ASCR, front contact c of relay16ASTR, through the winding of relay 1-6ASDR, and over back contact I)of relay 1-6ASDPSR to terminal N. With relays l-6ASTR and 1--6ASDRpicked up, a circuit is established for energizing relay 1--6A1CR, whichcircuit may be traced from terminal B at front contact :1 of relay1-6ASTR, Fig. 2b, through the blocking rectifier K, over front contactI) of relay 16B1CR, through the winding of relay 1-6A1CR, and over frontcontact h of relay 1-6ASDR to terminal N. When relay 1--6A1CR picks up,its front contact tr establishes a stick circuit for the relay whichcircuit may be traced from terminal B at from contact a of relay1--6A1CR, through the winding of the relay, and over front contact h ofrelay 1-6ASDR to terminal N.

When contact 1' of relay 1-6ASDR picks up, the con tact b of relay1-6ASTR is up at this time, and the circuit for supplying energy to thewinding of relay 1-6BSDR is interrupted, so that relay l-GBSDR rcleases.When relay 1-6BSDR releases, its front contact I) interrupts the circuitfor supplying energy to relay 16ASTR, and relay 1-6ASTR will bereleased.

With contact 1 of relay l-GASTR released, and contact i of relay I GASDRpicked up, a circuit is estab lished which includes front contact I) ofrelay 16A1CR. for supplying energy to the lamp A1 of the route stcrageindication lamp, so that this lamp now indicates that a route to storagetrack 1 is stored in the final storage bank of the initial storage unit.Additionally, the re lease of front contact ii of relay l-6BSDRinterrupts the circuit for supplying energy to the lamp B1 of the routestorage indication lamp so that this lamp is now extinguished. Therelease of contact g of relay 1-6BSDR interrupts the previously tracedstick circuit for relay 16B1CR, so that this relay releases, and at thistime the second or B bank of the initial torage unit is empty.

From the foregoing, it will be apparent that the entry of a routedescription into the initial storage unit of the system, by operatingone of the push buttons. causes the corresponding digital storage relayin the initial stor age bank of the unit to become picked up, and if lhesubsequent storage banks are empty. the digital storage relays in thesubsequent banks are picked up in sequence, with the storage relays inthe preceding hanks dropping out as soon as the storage is transferredto the next bank in advance. It will also be apparent that three storagecan be made, one in each of the three storage banks. the storagesproceeding as described above from the initial bank to the followingbanks until the next bank is found occupied, at which time the circuitsoperate to prevent the transfer of the storage to the following hank.Also it will be seen that the operator is provided with an indication ofthe storages present in the initial storage unit by means of the routestorage indication lamps, which are controlled over relatively simplecircuit: including the digital storage relays in the initial storageunit.

As previously pointed out, each route description is tored in theinitial storage unit in the form of a numerical or digit code in thebanks of the initial storage unit for the purpose of simplifying thecontrol of the route storage indication lamp. However, the numerical ordigit code is translated to a combination code from the final bank ofthe initial storage unit, and this combination code is employed togovern all of the switches including the initial switch. Moreover, thestorage units subsequent to the initial storage unit, namely the storageunits associated with each of the remaining switches in the systememploy combination codes for storing the route description. in thecombination code, a group of relays of which there are as many as themaximum number of switches in a route are provided, and the encrgized ordeenergized condition of these relays determine whether or not theswitch associated with that relay is to be operated to its normal orreverse position, the switch being operated to the reverse position ifthe associated combination storage relay is energized and being operatedto its normal position if the storage relay is deenergized. Accordingly,if the first switch storage relay in the storage bank is energized thefirst switch in the route will be controlled to the reverse position. Ifthe second switch storage relay in a particular storage bank isdeenergized the second switch in the route will be controlled to thenormal position, etc.

As previously pointed out, the switch position which leads to the leftas one looks from the hump toward the storage tracks is called thenormal position and the position leading to the right is called thereverse position. Referring'to Fig. l, to route a car or out of carsfrom the hump to storage track 1, it is necessary that switch 16 beoperated to its reverse position, switch 14 operated to its reverseposition, and switch 12 operated to its reverse position. Accordingly,under the operation being described, with a route description in theinitial storage bank for storage track 1, the combination switch storagerelays, namely relays 16A1WR, 1-6A2WR and 16A3WR, must all be energized,so that all of the switches will be operated to their reverse position.It will be noted that three switch storage control relays are providedin the initial unit, since there are a maximum of three switches in anyof the routes leading from the hump to any one of the switch storagetracks.

Since the digit storage relay in the A bank, namely relay 16A1CR, ispicked up at this time, its front contact establishes a circuit forsupplying energy to the winding of relay 16A1WR, its front contact destablishes a circuit for supplying energy to the winding of relay16A2WR, and its front contact e establishes a circuit for supplyingenergy to the winding of relay 16A3WR, so that all of the combinationswitch storage relays are energized at this time and their contacts arepicked up.

With the switch storage relays 16A1WR and 16A2WR picked up, and with thedetector track sections including switches 1--6 and 14 unoccupied, sothat track relays 16TR and 14TR are picked up, circuits are establishedfor operating the switches 1-6 and 1-4 to their reverse position, asnecessary to route a car for storage track No. 1 from the hump. Thereverse magnet RM of switch movement 16SM is energized at this time byenergy supplied over a circuit which may be traced from terminal B, overa contact a of the manual control lever 16MC in its center position,Fig. 2c, over back contact g of relay 16ZR,

front contact 1' of relay 16ASDR, back contact g of relay 1-6ASTR, frontcontact b of relay 16A1WR, front contact a of relay 16WPR, front contacta of track relay 16TR, through the winding of reverse magnet RM of theswitch movement 16SM, over contact Z of the switch movement closed inthe normal position, to terminal N. i

The contacts associated with the switch movement are shown in theposition which they occupy with the switch in its normal position, andare adjusted and arranged so that the contacts are operated from theirnormal or left-hand positions to their right-hand or reverse positionswhen the switch moves from its normal to reverse position. Additionally,the contacts Z are adjusted to open in the reverse position with theswitch points A" or other suitable distance from the full reverseposition of the switch and to close in the normal position with theswitch point open /2" or other predetermined distances slightly greaterthan the first distance from the reverse position. Accordingly, it willbe seen that at: this time the contact Z will maintain the previouslytraced circuit closed until the switch is within /2" of its reverseposition, at which time the contact Z will interrupt thecircuit to thereverse magnet RM. In

. release.

switches of the type usually employed in classification yards, theswitch movement is usually provided with toggle spring arrangements orother devices for maintaining the switch points in the position to whichthey were last operated after the supply of air to the operatingcylinder of the switch is cut off by the deenergization of the magnetcontrolling the admission of air to the cylinder. Accordingly, when theenergizing circuit for the reverse magnet RM is interrupted by contactZ, the holding mechanism will operate to move the switch to its fullreverse position, and to maintain it in that position with the air cutoff from the operating cylinder. The contact Y of the switch movement isarranged in a manner similar to that described for the contact Z exceptthat the normal contact is opened when the switch point is a slightdistance away from the normal position and the reverse contacts areclosed when the switch point moves a small distance further than thefirst distance from the normal position such as, for example, the normalcontacts may open with the switch A from the full normal position andthe reverse contact may close with the switch points z from normal.Accordingly, with the switch operated from normal to reverse the normalcontact of the contact Y will be open so that the circuit for energizingthe normal switch repeater relay 16NWPR, which is obvious from thedrawings, will be interrupted and relay 1-6NWPR will release. At thesame time, with contact Z now in its right-hand or reverse position acircuit will be established for supplying energy to the winding of thereverse switch repeater relay 1-6RWPR, so that this relay will pick upits contacts.

It will be noted that the switch restoring relay 16WPR is supplied withenergy at this timeby a circuit which may be traced from terminal B atcontact 2 of relay 16WPR, Fig. 2 which is picked up, through the windingof relay 16WPR and through the blocking rectifiers K to the normal andreverse indication circuits. Accordingly, it will be seen that the relay16WPR will be supplied with energy over this circuit as long as theswitch points are within A" from their full normal or full reverseposition. Since the switch movements are relatively fast in operation,the circuit for energizing the relay 16WPR will be interrupted only fora short time while the switch movement is operating from one position tothe other, unless, for some reason or other, the switch points should beobstructed so that the switch controller contacts do not complete theiroperation. In such 'case, the supply of energy will be cut oif for arelatively long time from the winding of relay 1--6WPR, and if this timeis longer than the release time of relay 16WPR, the relay will Upon therelease of relay 16WPR, its contact a will transfer the energizingcircuit previously traced for the reverse control magnet RM to a circuitincluding front contact e of the track relay 16TR which will energizethe normal control magnet NM, so that the switch movement will berestored to its normal position. Additionally, the release of contact eof relay 16WPR interrupts the stick circuit for relay 1--6WPR so thatthe relay remains released until such time as the car or cut of carsshunts the track relay 16TR, at which time the contact g of relay 16TRwill establish an energizing circuit for relay 1--6WPR, and if theswitch points are at that time in their full normal position the relay1--6WPR will be picked up again. During the time that contact e of relay16WPR is released energy is supplied to the winding of a coding device75CT, which may be of any suitable form well known in the railwaysignaling art, and comprises contacts which are recurrently operated ata specified rate, for example, 75 times per minute, when energy issupplied to the windings. With the winding of the coding device 75CT energized, energy is supplied over contact b of 75CT to a bell, causingthe bell to ring recurrently and thereby notifying the operator that aswitch obstruction has taken place.

As previously pointed out, switch indication lamps are provided on thecontrol board to indicate to the operator the position which aparticular switch occupies, when that switch is in the route for anapproaching car or cut of cars. in the particular instance presentlybeing described, with a route being set up to storage track 1, thereverse indication lamp l-tSRVt'K will be lighted by a circuit which maybe traced from terminal BX, at front contact I of relay 1-6TR, Fig. 20,over contact [1 on manual control lever l-GMC, through a current limiting resistor l-fiRW, front contact I: of relay 1-6ASDR, back contact I:of relay I-GASTR, front contact c of relay l-GAIWR, front contact (1 ofrelay ll-6WPR, front contact (I of relay l-GRWPR, and through the lampl-RWK to terminal NX. Accordingly, the lamp I-SRWK will be lighted at areduced voltage, since the current is flowing through the limitingresistor i-fiRW, to thereby designate to the operator that the switch1-6 is in its reverse position and that a car or cut of cars will berouted over switch 1-6 in the reverse position.

If. as previously pointed out, the switch machine l-6SM should be unableto complete its operation due to an obstruction in the switch points,the relay ll-o't viit will release and remain released, causingoperation of the coding device 75CT. In addition to sounding the warningbell, a contact a of relay 75CT reeurrently closes to supply energy fromterminal BX over contact a of the coding device 75CT, Fig. 2 backcontact c of relay l-6WPR. front contact (I of relay 1-6NWPR, andthrough the lamp il-GNWK to terminal NX. Accordingly, the lamp l-fiNWKwill be intermittently flashed, and since the voltage supplied to thelamp at this time is not reduced by the current limiting resistor, thelamp will flash brilliantly to thereby notify the operator which switchhas failed to complete its movement to the reverse position.

It is to be noted that at this time the manual control lever 1-6MC is inits center or automatic position, so that the operation of the switch1-6 is governed entirely by the operation of the automatic routingcircuit. However. manual operation may supersede the automatic operationat any time, by virtue of the operator operating the manual controllever 1-6MC to its left-hand or normal, or right-hand or reverseposition, depending upon the position to which the switch 1-6 is to beoperatcd. With the lever 1-6MC in its normal or reverse position, thecircuits for energizing the switch control magnet are carried over thecontacts of the detector track relay, in this case contacts d and e ofrelay 1-6TR, and are not affected by the operation of the switch storagerelays or the storage detector and transfer relays in the storage bankwhich controls the switch when on automatic operation. Moreover, it willbe seen that the operation of the switch restoring relay 1-6WPR has noeffect on the operation of the switch while the switch is being operatedmanually. The switch indication lamps are not governed by the automaticswitching circuits when the switches are being operated manually, butindieate only the correspondence between the control lever position andthe switch position. Additionally, the 1imiting resistor, such as l-GRW,is not included in the circuit at such times, so that the indicationlamps are lighted to full brilliance when the switch is controlledmanually.

The control and indication circuits for the switch 1 4- are similar tothose described above for the switch 1-6, with the exception that thecontrol and indication circuits for switch 1-4 include, in addition tothe contacts of switch storage relay 1-6A2WR which govern the positionof the switch, a front contact of the switch storage relay 1-6A1WR, thisarrangement being provided so that the switch 1-4 is governed by theautomatic switching circuits only when the switch storage relayl-fiAlWit is picked up to indicate that the preceding switch, namely 16switch 1-6, is to be reversed, so that the route will include switch1-4. If the switch 1-6 is to remain normal in accordance with the routebeing set up, then the contacts a and c of relay 1-6A1WR will bereleased, and the switch movement 1-4SM will not be operated at thistime.

However, in connection with the operation being described, that is, therouting of a car or cut of cars to storage track 1, it will be seen thatboth switches 1-6 and 1-4 should be reversed, and as previously pointedout. the switch storage relays l-tiAlWR, I-GAZWR and t-t/UWR, are allpicked up so that switch movement liSM is operated to operate the switch1-4 to it reverse position in view of the fact that the relays l-fiAlWRand 1-6A2WR are both picked up.

The operations described above are all carried out prior to the timethat the car or cut of cars proceeding from the hump yard arrive at thedetector track section associated with the switches 1-6 and 1-4. Aspreviously pointed out, when the car or cut of cars enters the tracksection associated with the switches, the track relay t-GTR will releaseand remain released during the time that the car or cut of cars occupiesthe track between the limits designated by the arrows indicated with thereference character P and the track relay 1-4TR will be released duringthe time that the car or cut of cars occu pies the track stretch betweenthe limits designated by the arrows associated with the referencecharacter 0. When relay 1 6TB. releases, its front contacts (I and einterrupt the circuit for the control of the normal and reverse controlmagnets of switch movement 1-6SM, so that the switch movement cannot beoperated while the car or cut of cars is moving over this portion of thelap switch layout. When the car or cut of cars causes the release ofrelay ltTR. the supply of energy to the control magnets of the switchmovement 1-4SM is cut off, so that this switch cannot be operated whilethe car or cut of cars is preceding over it. It will be apparent thatthe track relayl-GTR will pick up again when the rear wheels of a car orcut of cars moves off the track section indicated by the limitsassociated with the reference character P, so that switch 1-6 can beoperated at this time even though the car or cut of cars has not clearedthe following switch 1-4 of the lap switch layout.

The occupancy of: the various detector track sections is indicated tothe operator of the machine by the lighting of the associated trackindication lamp, such as lamp l-fiTK, governed by an obvious circuitincluding back contact 1 of relay 1-6TR.

The automatic switching circuits are devised and arranged in such mannerthat the route description is forwarded from the initial storage unit,which governs the lap switches, to the storage unit associated with thetrack switch 1-2, at the time that the car or cut of cars enters thedetector track section of the preceding switch, in this case the lapswitches 1-6 and 1-4.

As previously described, the relay I-GASDR is encrgized at this time bya circuit which includes the back contact b of relay I-GASDPSR. When thecar or cut of cars destined for the storage track 1 enters the secondportion of the detector track section at the switches 1-6 and 1-4, therelay 1-4TR will release, and a pick up circuit will be provided forenergizing relay l-GASDPSR. This circuit may be traced from terminal Bat front contact g of relay 1-6ASDR, Fig. 211, over back contact 0 ofrelay 1-6ASTPSR, back contact I of relay 1-6ZR, front contact a of relay1-6A1WR, back contact a of relay 1-4TR, and through the winding of relay El-GASDPSR to terminal N. When the relay t-tSASDPSR picks up, astick circuit for this relay is established which may be traced fromterminal B at front contact g of relay 1-6ASDR, Fig. 21), over frontcontact a of relay 1-6ASDPSR, and through the winding of relay l-GASDPSRto terminal N. Accordingly, it will be seen that once relay 1-6ASDPSRpicks up, it

will releaseonly upon the release of relay 16ASDR, which indicates thatthe route description has been forwarded to the next storage unit. Thepicking up of contact b of relay 16ASDPSR interrupts the stick circuitfor relay 16ASDR, which was previously traced, but at this time a secondstick circuit is established so that relay 1'6ASDR is not released. Thissecondstick circuit may be traced from terminal BA at the push button1-6ACPB, Fig. 212, over back contact a of relay 1'6ASCR, over frontcontact at of relay 16ASDR, through the winding of relay 16ASDR, overthe back contacts [2 of relays 1-6TR and 14TR in multiple, over the backcontacts 2 of relays -6BSTR and 5-6BSDR in multiple, over the backcontacts .2 of relays 3-4BSTR and 34BSD R in multiple, and over the backcontacts 0 of relays I-ZBST R and 12BSDR in multiple to terminal N.

At this time, it will be considered that there are no storages in theinitial storage bank of the storage unit associated with the switch 12.Accordingly, relay 12BSDR will be released. Under these circumstances, acircuit is established at this time for energizing the storage transferrelay associated. with the initial or B bank of the storage unitassociated with switch 12. This circuit may be traced from terminal B atback contact e of relay 16ASTR, Fig. 212, over front contact 0 of relay16ASDPSR, front contact 0 of relay 16RWPR, front contact a of relay14RWPR, back contact 0 of relay 12BSDR, and through the winding of relay12BSTR to terminal N. When relay 12BSTR picks up, it establishes a stickcircuit for itself which circuit may be traced from terminal B at frontcontact a, of relay 16ASDR, over front contact a of relay 12BSTR, andthrough the winding of relay 12BSTR to terminal N. At this time, eventhough back contact 2 of relay 1.2BSTR in the stick circuit for relay1-6ASDR previously traced is open, relay 16ASDR will continue to beenergized, since relay 12BSDR is still released at this time and itsback contact e maintains the stick circuit previously traced for relay16ASDR. When the relay 12BSTR picks up, its front contact establishes acircuit for energizing relay 16ASTPSR, which circuit may. be traced fromterminal B at front contact 1 of relay 12BSTR, Fig. 2g, and through thewinding of relay 16ASTPSR to terminal N. When the relay 16ASTPSR picksup, its front contact a establishes a stick circuit for the relay whichmay be traced from terminal B at back contact 0 of relay 1 4TR, Fig. 20,over front contact a of relay 16RWPR, over front contact a of relay16ASTPSR, and through the winding of the relay to terminal N. Byproviding a stick circuit for relay 16ASTPSR which includes a backcontact of the track relay associated with the section, the relay1-6ASTPSR is prevented from picking up more than once during the trackcircuit occupancy. Moreover, since back contact 0 of relay 16ASTPSR isin the pick up circuit for relay 16ASDPSR, the relay 16ASDPSR isprevented from picking up more than once during the occupancy of theassociated track circuit.

When relay 12BSTR picks up, a circuit for picking up the storagedetector relay 12BSDR is established, which circuit may be traced overthe back contacts b of relays 12ASTR and 12ASDR in multiple, Fig. 2g,over front contact b of relay 12BSTR, and through the winding ofrelay12BSDR to terminal N. When relay 12BSDR picks up, its front contact aestablishes a stick circuit which bypasses the front contact 12 of relay12BSTR, so that relay 12BSDR will remain picked up following the releaseof relay 12BSTR.

With relays 12BSTR and 12BSDR picked up, a circuit is now establishedfor transferring the route storage from the initial storage unit to theinitial or B bank of the storage unit associated with switch 12. This isaccomplished by picking up the switch storage relay 1 2B1WR which is theinitial switch storage relay in the storage unit associated with switch12. The circuit may be traced from terminal B at front contact a ofrelay 16A3WR, Fig. 2b, over front contact d of relay 12BSTR, through thewinding of relay 12B1WR, and over front contact d of relay 12BSDR toterminal N. When relay 1 ZBIWR picks up, it establishes a stick circuitfor itself which may be traced from terminal B over front contact a ofrelay 12B1WR, through the winding of the relay, and over front contact dof relay 12BSDR to terminal N.

When relay 12BSDR picks up, its back contact 2 interrupts the previouslytraced stick circuit for relay 16ASDR, so that relay 16ASDR will releaseafter a short interval. When front contact g of relay 1- 6ASDR releases,the supply of energy to relay 1 ASDPSR is cut off, so that relay16ASDPSR releases following the release of relay 16ASDR. When contact hof relay l--6ASDR releases, it interrupts the stick circuit for thedigital storage relay 16A1CR, so that relay 16A1CR releases. Release ofcontact i of relay 16ASDR interrupts the supply of energy to indicationlamp A1. The release of contact b of relay 1--6A1CR further interruptsthe circuit for supplying energy to the storage indication lamp A1. Therelease of contacts 0, d and e of relay 16A1CR interrupts the supply ofenergy to the switch storage relays 16AlWR, 1 6A2WR and 16A3WR and theserelays release. This operation completes the transfer of the routedescription from the initial storage unit associated with the lapswitches, to the initial bank of the storage unit associated with switchll-2.

Considering now the further operation of the apparatus associated withthe storage unit at which 12, the release of contact a of relay 1 -6ASDRinterrupts the stick circuit for relay 12BSTR, and since the pick upcircuit for relay 12BSTR is open at back contact c of relay 12BSDR, relay 12BSTR will release. The release of contact a! of relay 12BSTR opensthe pick up circuit for relay 12B1WR, but, as previously pointed out,the relay 12B1WR is provided with a stick circuit at this time includingfront contact d of relay 12BSDR and this relay remains picked up. Withrelay 12BSTR released and 12BSDR picked up, a circuit is established forpicking up relay 12ASTR to initiate the transfer of the switch storageto the final or A bank of the 12 storage unit. This circuit may betraced from terminal B at back contact c of relay 12BSTR, Fig. 2g, overfront contact b of relay 12BSDR, over back contact a of relay 1lASDR,and through the winding of relay l-ZASTR to terminal N. When contact aof relay 12ASTR picks up, it establishes a stick circuit for the relaywhich bypasses the back contact a of relay 12ASDR. When contact b ofrelay l-ZASTR picks up, it interrupts its connection to the stickcircuit of relay 12BSDR, but the circuit remains closed over backcontact b of relay 12ASDR, so that relay 1-- ZBSDR remains picked up atthis time. When front contact 0 of relay 1-2 ASTR closes, a circuit isestablished for energizing relay 1-2AS DR, which circuit may be tracedfrom terminal B at the cancellation push button l-ZAPB, Fig.'2g, overfront contact 0 of relay 12ASTR, over front contact a of track relay172TR, and through the winding of relay 12 ASDR to terminal N. Whenrelay 12ASDR picks up, its back contact a interrupts the pick up circuitfor relay 12AS,TR,- but relay 12ASTR remains energized over the stickcircuit previously traced. The pick up of contact I) of relay l-ZASDRcuts off the supply of energy to the stick circuit of relay 12BSDR, butsince relay 1- ZBSDR is of the slow release variety, its contacts willremain in their picked up position for a predetermined time intervalafter the supply of energy is discontinued to the relay winding. Thepick up of front contact 0 of relay 12ASDR establishes a bypass aroundthe front contact c of relay 12ASTR in the circuit .g overning relay1-2ASDR, so that relay 1-2ASDR will remain picked up after thesubsequent release of relay 1-2ASTR. Front contact a. of relay 1--2ASTRand front contact a of relay 1-2ASDR are closed at this time, and acircuit is now established for energizing the switch storage relay1-2A1WR, which circuit may be traced from terminal B at front contact bof relay 1 ZBIWR, over front contact d of relay 1-2ASTR, through thewinding of relay 1--2A1WR and over front contact e of relay 1-2ASDR toterminal N. The pick up of relay 1-2A1WR provides a stick circuit formaintaining the relay energized which includes front contact a of relay12A1WR and front contact e of relay 1--1ASDR.

When relay 1--2BSDR releases at the end of its release time, its frontcontact d interrupts the stick circuit for the switch storage relay1--2B1WR, and relay 1- 2B1WR releases opening the pick up circuit forrelay 1-2A1WR, which relay remains picked up at this time because of thestick circuit previously traced. The release of contact 11 of relay1--2BSDR interrupts the circuit for supplying energy to relay 1-2ASTR,and relay 1-2ASTR will thereby be released at this time.

With relay 1-2ASTR released, relay 1-2AIWR picked up, and relay 1-2ASDRpicked up, assuming that the route storage transfer to bank A has beencompleted, the circuit for governing switch 1-2 to its reverse positionwill be completed. As previously pointed out, the circuits forcontrolling the switches 5-6, 3-4 and 1-2, are identical and it will beapparent by reference to the typical circuits shown for the singleswitches on Figs. 2:! and 2e, that at this time with the relays in thefinal storage bank of the 1-2 storage unit in the condition aspreviously described, the switch control circuit will be closed tooperate the switch to its reverse position, and the switch indicationcircuit will provide a reverse switch indication on the control board,showing that the car or cut of cars will proceed over switch 1-2reversed to storage track 1.

At this time, considering the apparatus in the initial storage unit, therelay 1--6ASDR can now pick up again if there is a subsequent storage inthe B bank of the initial storage unit. However, at this time relay 1-6ASTPSR is picked up since the car or cut of cars is still occupying thelatter portion of the track circuit over switch 1-4, so that the backcontact of relay 1-4TR maintains the stick circuit for relay 1-6ASTPSR.With relay 1--6ASTPSR picked up, so that its back contact c is open, therelay 1-6ASDPSR cannot pick up at this time, and accordingly a newstorage which is transferred from storage bank B to the final storagebank in the initial storage unit cannot be further transferred to theinitial storage bank associated with any of the single switch locations12, 3-4 and -6. In other words, with front contact 0 of relay 1-6ASDPSRopen, the circuit for energizing the storage transfer relays, such asrelay 1-2BSTR, in each of the storage units associated with the finalswitches is open, and the storage transfer relays cannot be energized atthis time.

It is to he pointed out that if the storage unit for switch 12 had beenfull when the car or cut of cars destined for storage track 1 firstentered the detector section 14 at the lap switch location, relay 12BSDRwould be picked up and consequently the storage transfer relay 12BSTRcould not pick up at this time since this pick up circuit would be openat back contact 0 of relay 1-2BSDR. Accordingly, the route descriptioncould not be forwarded at this time from the initial storage unit to thestorage unit at switch location 1-2. If the route description had notbeen transferred from the initial unit to the storage unit associatedwith switch 12 by the time the car or cut of cars vacated the detectorsection and track relay 1-4TR picked up, the route description would becancelled automatically in the initial storage unit, since the pickingup of relay 1-4TR interrupts the stick circuit for relay 1-6ASDR, withthe re- 20 sult that relay 1-6ASDR would release. The release of relay1-6ASDR would cause the release of relay 1--6ASDPSR, and with relay16ASDPSR released there would be no circuit established for energizingthe relay 1-2l3STR to transfer a route description from the initialstorage unit to the storage unit for switch 12.

Assuming that the switch storage previously described to route the caror cut of cars to track 1 has been entered in the storage unitassociated with switch 1--2 and has cascaded from the initial to thefinal bank, thereby causing operation of the switch 12 to its reverseposition, it will now be assumed that the car or cut of cars, havingleft the lap switch location has preceded further down theclassification track and now enters the detector track sectionassociated with switch 1-2, so that the track relay 1-2TR is released.

When contact a of relay 1-2TR releases, it interrupts the circuit forenergizing the relay 12ASDR, and relay 1-2ASDR releases after a shorttime interval. The release of contact :1 of relay 1--2ASDR establishes acircuit for energizing relay 1-2ASDPSR, which circuit may be traced fromterminal B at back contact b of relay 1--2TR, Fig. 2g, over back contact:1 of relay 12ASDR, and through the winding of relay 12ASDPSR toterminal N. When relay 1-2ASDPSR picks up, its front contact 0establishes a stick circuit including the back contact I) of relay1-2TR, so that relay 1-2ASDPSR will remain energized as long as thedetector track section is occupied. The picking up of contact I) ofrelay 1-2ASDPSR establishes a circuit for reenergizing relay 1-2ASDRshould a subsequent storage be present in the initial bank of the 1--2storage unit at the time. Accordingly, a subsequent storage occupyingthe initial storage bank of the 1-2 storage unit can be transferred tothe final or A storage bank at this time even though the detector tracksection relay is released, since relay 1-2ASDR can be energized by acircuit including the front contact b of relay 1-2ASDPSR which bypassesthe front contact a of relay 1--2TR in the pick up circuit for relay1--2ASDR. If such subsequent storage is made, when the preceding car orcut of cars vacates the detector track section, relay 1--2TR will pickup and its front contact a will reestablish the circuit for energizingrelay l-2ASDR, and at the same time, the picking up of contact [1 ofrelay 1-2TR will deenergize relay 1-2ASDPSR, so that contact b of relay12ASDPSR in the pick up circuit for relay 1-2ASDR will be open.

The foregoing description illustrates the manner in which a routedescription is entered in the initial unit of the machine, and iscascaded through the various storage banks in the initial unit, withroute storage indications being provided to the machine operator toindicatc what routes may be stored in the initial unit. Also, theoperation of the apparatus and the forwarding of route descriptions fromthe initial unit to the units associated with the following switches inthe classification yards have been described, together with the mannerin which the switches at the various locations are operated inaccordance with the route descriptions stored for that location.

Under certain operating conditions, for example, the

discovery that a car or cut of cars should be routed to a differenttrack from that which was designated in storing the route in the initialunit, the operator may wish to cancel one or more route descriptionsthat have been stored in the initial unit. In order to provide for suchcancellation, there is provided a cancellation push button 1-6CC, Fig.2b, which governs a series of cancellation relays, one for each storagebank in the initial storage unit, as represented by the cancellationrelays 1-6CSCR, 16BSCR and 16ASCR, Fig. 2b. The circuits for governingthe cancellation relays are arranged in such manner that the routesstored in each of the storage banks of the initial storage unitbeginning with the initial stor-' agebank and ending with the finalstorage bank are can.- celle'd by sequential operation of thecancellation push button. When the cancellation relay associated withthe particular storage bank is picked up, it opens the stick circuit forthe corresponding storage detector or SDR relay associated with thatbank, with the exception of the initial storage bank, where the pickingup of the cancellation relay associated with that bank opens the stickcircuit for the storage relays themselves, with the result that a pickup of the cancellation relay associated with the particular bank causesthe route description stored in that bank to be cancelled. Consideringthe detailed operation of the cancellation circuits, it will be assumedthat a route is stored in the final or A bank of the initial storageunit, and that a route description stored in the intermediate or B bankof the initial storage unit is to be cancelled. When the cancellationpush button 1-6CC is depressed, a circuit is established for picking upthe cancellation relay 1-6BSCR associated with the B storage bank of theinitial storage unit. This circuit may be traced from terminal B at thepush button contact, Fig. 2b, over a back contact b of relay 1'-6CSDR,back contact d of relay 16CSCR, over a front contact d of relay 16BSDR(the relay 1-6BSDR being picked up at this time because a storage ispresent in the B bank of the unit), and through the winding of relay16BSCR to terminal N. When relay 16BSCR picks up, it establishes a firststick circuit for itself including a front contact b of relay -16BSCR,which stick circuit may be traced from terminal B over the push buttoncontact, Fig. 2b, over back contact b of relay 1-6CSDR, back contact dof relay 16CSCR, over front contact I; of relay 1-6BSCR, and through thewinding of relay 1-6BSCR to terminal N. This stick circuit is, ofcourse, maintained as long as the cancellation push button is depressed.If the operator releases the cancellation push button before the routestorage in the B bank has been cancelled, the relay 1-6BSCR will stillremain energized through the medium of a second stick circuit which maybe traced from terminal B at front contact e of relay 16BSDR, Fig. 2b,over front contact a of relay 1-6BSCR, and through the winding of therelay to terminal N. The pick up of the contact of relay 16BSCR opensthe circuit for energizing the storage detector relay 16BSDR, and relay1-6BSDR will thereupon release. Upon the release of relay 1-6BSDR, itscontacts will open the stick circuit for the digital storage relays suchas relay 1--6B1CR in the storage bank B of the initial storage unit, sothat any of the relays in the B storage bank which are picked up will bereleased at this time. When the contacts of relay 16BSDR release, thepreviously traced pick up and second stick circuit for relay 1-6BSCR areopen, and if the operator has released the cancellation push button atthis time, relay 1-6BSCR will release, thereby restoring thecancellation circuits to their normal condition.

If at this time it shoud be also decided to cancel the route storage inthe A bank of the initial storage unit, the operator will again depressthe cancellation push button 16CC, which will provide a circuit forenergizing the cancellation relay 16ASCR associated with the final orstorage bank A of the initial storage unit. This circuit may be tracedfrom terminal B at the contact of the cancellation push button, Fig. 2b,over back contact I) of relay 1-6CSDR, back contact d of relay 1-6CSCR,back contact a of relay l-6BSDR, back contact 0 of relay 16BSCR, overfront contact d of relay 16ASDR, and through the winding of relay1-6ASCR to terminal N. Relay 1-6ASCR is provided with a first and secondstick circuit similar to those described for relay 16BSCR, so that relay1-6ASCR when once picked up will remain picked up until the routestorage in the final bank of the initial storage unit is cancelled bythe release of the storage detector relay 1-6ASDR associated with thatstorage bank, or until the operator releases the push button 1--6CC,whichever occurs later.

Additionally, as shown in- Figs. 2b, 2d and 2g, each of the storagedetector relays associated with the final storage bank in each of thestorage units, such as relays 1-6ASDR, 1'2ASDR, 34ASDR and 5-6ASDR, isprovided with a cancellation push button in the control circuits for therelay, such as push button 12APB associated with relay 12ASDR. Operationof this push button will cause the release of the storage detectorrelays associated with the final storage bank in each of the variousstorage units including the initial storage unit. Accordingly, if theoperator wishes to cancel the storage in the final storage bank of anyunit, he may operate the associated cancellation push button which willthereby deenergize the storage detector relay asso ciated with the finalstorage bank in that particular unit to thus cause the route storage inthe final bank of that unit to be cancelled.

One other cancellation feature is provided in my system, in that theenergy supplied to the various SDR or storage detector relays in eachbank of the initial storage unit, as well as the energy supplied for theindication lamps, is carried over contacts of a clear system push buttonCSPB, so that, if this push button is operated, all power is cut off thestorage detector relays in each of the storage banks, and additionallythe power is cut oif the various indication lamps. Thus the storagedetector relays for all the banks will be simultaneously released, whenthe push button is depressed, and at the same time, all the indicationlamps will be extinguished, so that the lamps will not flash during thetime that the indications are being cancelled. It will be seentherefore, that all of the route descriptions stored in the initialstorage unit may be cancelled simultaneously by operating the clearsystem cancellation push button.

As previously pointed out, the manner in which the switches of a lapswitch layout are governed is extremely important in systems of the typeherein described. If only one detector track section is employed, thecircuit arrangement is somewhat similar to that provided for a singletrack switch. However, the use of a single detector track section forthe lap switch layout greatly reduces the speed of classification, sinceneither of the switches can be lined up for a following cut of carsuntil the preceding cut of cars has cleared both switches. If separatedetector track sections are employed, then the first switch of the lapswitch layout is free to operate as soon as a cut of cars vacates thefirst section, and before the second section is vacated. To provideoperation of the first switch in a lap switch layout while the detectortrack section associated with the second switch is still occupied, inorder that a route can be lined up for a "following cut before the firstout has vacated the second detector section, I provide an auxiliaryrelay such as relay 1-6ZR, Fig. 2e. This relay is controlled by theswitch repeater relays of the first switch of the lap switch layout andby the route storage relays in the bank preceding the final bank whichnormally controls the switch operation, so that under conditions wherethe first cut of cars moves over the first and second switches of thelap switch layout, but the next cut of cars will move over the firstswitch only, the auxiliary relay becomes picked up. The contacts of theauxiliary relay govern the operation ofthe first switch of the lapswitch layout and additionally govern the operation of the storagetransfer circuits for the storage units following the unit which governsthe lap switch layout, so that the proper routing is obtained.

There are three operating conditions involving the lap switches andthese conditions will now be described, in order that the purpose andutility of the auxiliary relay ZR will be made clear. Each of theseconditions involves two successive cars or cuts of cars proceeding fromthe hump and over the lap switches to various storage tracks.

The first condition is that in which the two successive cuts are beingrouted over switch 1-6 normal. Under this condition, the second switch1-4 is not involved for either route, since switch 1-6 is normal foreach cut, and the circuits operate in a manner similar to that alreadydescribed for a single cut of cars being routed to track 1. Aspreviously described, switch 1-4 includes in its control circuits frontcontacts d and e of relay 1-6A1WR, so that switch 1-4 is not operatedunless relay 1-6A1WR is picked up, indicating a route to tracks 1through 4. Accordingly, two successive cuts routed over switch 1-6normal will not require switch 1-4 to be operated. The route descriptionfor the two successive cuts moving over switch 1-6 normal will betransferred to the storage unit associated with switch 5-6 when the cutsenter the first track section at the lap switches. At this time, relayI-GASDPSR is energized by a circuit which may be traced from terminal Bat front contact g of relay 1-6ASDR, Fig. 3b (which is picked up at thistime since a route storage exists in the final bank of the initialstorage unit), over back contact c of relay l-GASTPSR, back contact (Iof relay 1-6ZR, back contact a of relay 1-6A1WR, back contact a of relay1-6TR, and through the winding of relay 1-6ASDPSR to terminal N.Accordingly, relay I-GASDPSR picks up and sticks up over a stick circuitincluding its own front contact a and front contact g of relay 1-6ASDR.Relay 1-6ZR remains released at this time since its pick up circuit isopen at front contact b of relay 1-6RWPR.

With relay 1-6ASDPSR picked up, a circuit is established for energizingthe transfer relay S-GBSTR associated with switch 5-6. This circuit maybe traced from terminal B at back contact e of relay 1-6ASTR, Fig. 2b,over front contact c of relay I-GASDPSR, front contact c of relayl-GNWPR, back contact of relay 1-6ZR, back contact 0 of relay -6BSDR,and through the winding of relay 5-6BSTR to terminal N. When relayS-GBSTR picks up, it establishes a stick circuit including its own frontcontact a and front contact a of relay 1-6ASDR, which insures that relayS-GBSTR will remain picked up until the route storage is transferredfrom the initial storage unit. With relay 5- GBSTR picked up, a circuitis established for picking up relay 5-6BSDR, which circuit includesfront contact I) of relay 5--6BSTR. With relays S- SBSTR and 5-6BSDRpicked up, the route storage will be transferred from the initialstorage unit to the storage unit associated with switch 5-6. I

The action described above takes place for both the first and second cutof cars under the condition where both cuts are routed over switch 1-6normal.

The second condition to be considered is that wherein two successivecuts have their destination to tracks 1 through 4, so that the cuts moveover switch 1-6 re verse, and switch 1-4 either normal or reverse. Underthis condition, the two switches will be operated simultaneously, andthe route description will be transferred to the next storage unit whenthe second track section is occupied, i. e., when relay ltTR releases.The detailed circuit operation is similar to that described originallyfor a cut of cars moving to storage track 1, and further description isdeemed unnecessary.

The third condition, which involves the operation of relay 1-6ZR, isthat in which the first cut moves over switch 1-6 reverse and overswitch 1-4 normal or reverse, and the second cut moves over the switch1-6 normal. For example, let it be considered that the first cut isdestined for storage track 1 and the second cut is destined for storagetrack 5.

The route descriptions are entered in the initial storage bank in themanner previously described, by operation of push buttons IPB and SP8 insuccession. Assuming that the initial storage unit is vacant at thetime, relays 1-6C1CR, 1-6B1CR and 1-6A1CR will be operated in successionafter the operator depresses push button IPB, so that the routedescription cascades to the final or A bank of the initial storage unit.The relays 1-6C5CR and 1-6B5CR will then be operated in sequence afterthe operator depresses push button SPB. The detailed circuit operationis similar to that previously described and need not be repeated indetail. Accordingly, the two routes will be stored in the final bank andthe next preceding or penultimate bank of the initial storage unit, asindicated by relays 1-6A1CR and 1-6B5CR being picked up.

With relay 1-6A1CR picked up, switch storage relays 1-6A1WR, l-GAZWR andl-GAZWR will be picked up by the previously traced circuits includingfront contacts 0, d and e of relay Ll-GAICR. At this time therefore, thecontrol circuits for switches 1-6 and 1-4 will be energized to operateswitch 16 reverse and switch 2-4 reverse.

At this time, with the first switch in the lap switch layout, namelyswitch 1-6, in its reverse position, and with a storage existing for asecond cut which requires switch 1-6 to be operated to its normalposition, it will be assumed that the first cut moves over the lapswitches so that relay 1-6TR and 1-4TR are released in sequence. Sincecontact a of relay 1-6A1WR is picked up at this time, relay I-GASDPSRwill he picked up when the first cut causes the release of contact a ofrelay -4TR, by energy supplied over the circuit previously traced. Whenrelay I-GASDPSR picks up, it establishes a previously traced stickcircuit for keeping the relay picked up until the transfer of the routestorage is completed.

When relay 1-6ASDPSR picks up, a circuit is established for energizingrelay 1-6ZR, which circuit may be traced from terminal B at frontcontact e of relay l-GBSCR, Fig. 20, over front contact I) of relayI-GRWPR, front contact a of relay 1-6ASDPSR, and through the winding ofrelay l-GZR to terminal N. When relay 1-6ZR picks up, it establishes afirst stick circuit for itself including its own front contact 0 andfront contact a! of relay I-GASDPSR. The circuit for initiating thetransfer of the route description from the initial storage unit to thestorage unit associated with switch 1-2, by picking up relay l-QBSTR. isnow completed, and is the same circuit previously traced.

When the first cut Vacatcs the first track section. so that relay l-6TRpicks up, a circuit is established for operating switch 1-6 to itsnormal position. This circuit may be traced from terminal B, over thecontact a of the switch control lever 1-6MC in its center or automaticposition, Fig. 2c, over front contact g of relay 1-6ZR, front contact :1of relay t-GBSCR. hack contact i of relay L-GBSTR, front contact I) ofrelay l-6WPR, front contact 0 of relay l-GTR, through the normal magnetNM of switch movement l-GSM. and over reverse contact Y of the switchmovement circuit controller to terminal N. Accordingly, switch 1-6 isoperated to its normal position, as required by the following cut. Whenrelay 1-6NWPR picks up, a second stick circuit for relay 1-6ZR iscompleted. which extends frorn terminal B over front contact i of relay1-6NWPR (Fig. 20), front contact I, of relay 1-6ASTPSR, front contact 11and the winding of relay 1-6ZR to terminal N. The effect of this circuitis to hold relay 1-6ZR energized until relay 1-6ASTPSR releases, whichin this particular situation occurs a short time after the release ofrelay l-ZBSTR since both stick circuits for relay I-GASTPSR are alreadyopen. This sequence of operations is necessary, as will appear shortly,to prevent any misrouting of the route descriptions.

Thus it will be seen that the first switch of the lap switch layout canbe operated for the following cut even though the first cut may not havevacated the second detector section. This operation could not, ofcourse, be obtained with only a single detector track section.

The transfer of the route description of the first cut

